The present invention relates to a device for producing intertwining knots in a multifilament thread.
A device for producing intertwining knots in a multifilament thread is known from DE 41 40 469 A1. In the production of multifilament thread it is generally known that the cohesion of the individual filament strands in the thread is produced by so-called intertwining knots. Such intertwining knots are produced by a compressed air treatment of the thread. In this connection, depending on the thread type and process, the desired number of intertwining knots per unit of length as well as the stability of the intertwining knots can be subject to differing requirements. For example, in the production of carpet yarns, which are processed immediately after a melt spinning process, a high knot stability as well as a high number of intertwining knots per unit of length of the thread is desired.
In the case of higher thread speeds, in order to achieve a relatively high number of intertwining knots, the known device has a rotating nozzle ring that interacts with a stationary stator. The rotating nozzle ring has a thread guide groove on the periphery into whose groove base over the periphery several uniformly distributed, radially aligned nozzle bores open. The nozzle bores penetrate the nozzle ring from the guide groove to an inner casing, which is guided on the periphery of the stator. The stator has an inner pressure chamber, which is connected by a chamber opening constructed on the periphery of the stator. The chamber opening on the stator, as well as the nozzle bores in the nozzle ring lie on a plane, so that in the event of rotation of the nozzle ring, the nozzle bores are fed in succession to the chamber opening. The pressure chamber is connected to a compressed air source so that, during the interaction of the nozzle bore and the chamber opening, a compressed air jet is produced in the thread guide groove of the nozzle ring.
The stator has an encircling sliding surface for guiding the nozzle ring, which interacts with a sealing surface constructed on the inner casing of the nozzle ring. In order to achieve the lowest possible loss of compressed air during the transfer of the compressed air from the pressure chamber to the nozzle bore of the nozzle ring, a sealing gap is formed between the sealing surface of the nozzle ring and the sliding surface of the stator. In this connection, it is necessary to design the longest possible distinctive sealing gaps at both sides of the nozzle ring in order to achieve the lowest possible losses of compressed air. However, such gap seals require a very narrow gap in order to obtain an effective sealing in spite of a gap length. However, a narrow gap is only possible through high production expenditure. In addition, gaps that are too narrow between the sealing surface of the nozzle ring and the sliding surface of the stator can lead to friction and thus considerable wear and tear issues through operational influences such as for example the centrifugal force, imbalance phenomena or heat development.